In an instrument panel in a vehicle, there are a manipulation area, formed of a plurality of switches for manipulating in-vehicle devices, and a displaying area, for displaying operating states of the in-vehicle devices. Recently, appearance of an intelligent transport system (ITS) represented by a navigation system and an adaptive cruise control system (ACC) exhibits increasing of the number of the in-vehicle devices and enhancing performance of the in-vehicle devices. The switches for manipulating the in-vehicle devices thereby have a tendency to increase. Therefore the instrument panel needs to be designed so that the manipulation area and the displaying area can be arranged with user-friendliness in a limited area of the instrument panel.
An instance shown in FIG. 6A is proposed for an in-vehicle-device system. This in-vehicle-device system includes a panel electronic control unit (ECU) 3, a manipulation panel 1, and a display 2. The panel ECU 3 is communicated with various ECUs 4, 5, 6 via a multiplex signal line 7. The manipulation panel 1 is a manipulation area through which a user selectively operates an in-vehicle device. The manipulation panel 1 includes a set of function keys 11, a dial 12, a directional switch 13, and the like. The set of the function keys 11 are used for calling a manipulation menu of each in-vehicle device including a navigation system, an air-conditioner, and an audio. When the user wishes to modify a blow mode of the air-conditioner, a function key 11 corresponding to a manipulation menu for the air-conditioner is selected. The manipulation menu including a plurality of manipulation items is thereby displayed as shown in FIG. 6B. The user then selects a necessary manipulation item from the menu through manipulating the directional switch 13 to modify the blow mode. Similarly in the navigation system and the audio, the user operates each in-vehicle device by selecting a necessary manipulation item with a corresponding function key 11 and the directional switch 13.
Thus displaying respective manipulation menus for the in-vehicle devices on the display 2 and adopting the directional switch 13 for a common manipulation area are designed to decrease the number of manipulation parts or displaying areas.
However, in the above in-vehicle-device control system, the manipulation menu displayed on the display 2 includes many items in one display window as shown in FIG. 6B. In addition, one display window also displays, every in-vehicle device, various manipulation menus also including many manipulation items. It is therefore difficult for the user to quickly select a necessary item, which results in involving a useless manipulation period up to completing to operate a necessary in-vehicle device.